For some reason, redirecting cache's logger to '/dev/null' resulting in
a test failures and LoadError. I think it's because of Thread issue.
Instead of trying to make every logger threadsafe for Rails 3.2, I think
it's better to just don't set the logger for now.
(Note: resetting the logger back to original value in the teardown block
didn't fix the problem.)

Ruby 2.0 changed the behavior of `respond_to?` without argument to
return only search for public method. We actually want to perform the
action only if `method_missing` is either in public or protected.